GB2125050A - Finely-divided polymer compositions - Google Patents

Abstract

A solid finely-divided composition comprises a substrate i.e. carrier and a carboxylated polyalkene. Such compositions can have desirable rheological properties. They may be prepared by absorption/adsorption into/onto the substrate, optionally using a solvent, followed by grinding, or by coprecipitation followed by grinding.

Description

SPECIFICATION Finely-divided polymer compositions There are currently various materials and compositions available to reduce the rate at which pigments settle in solvent-based systems, to increase viscosity, to decrease sagging or running of pigmented systems after application to surfaces, or to otherwise affect the rheology. Among the materials used are soaps of various kinds, powdered waxes such as hydrogenated castor oil, organicallymodified bentonites, and pigments of particular particle shapes or those having high surface areas.

More recent types of compounds, carboxylated polyethylenes, are supplied as a paste in organic solvents. The compounds of this general type are described in US--AA-3,123.488, 3,1 84,323, 3,557,037 and 3,407,160.

These materials differ from the neutral polymers widely used for purposes such as sheeting or extruded or moulded articles, in that they have a degree of acidity, i.e. they have acid numbers. This acidity is obtained by copolymerisation of ethylene (sometimes with other alkenes) with acidic monomers, by oxidation of Fischer-Tropsch and other similar resins or waxes; for example, US-A-3,407,1 60 describes reacting a polyolefin with acidic materials under conditions wherein free radicals are formed (high temperature and peroxides).

Commercially-available examples of such carboxylated polyolefins are Ailied Chemicals AC-629, 655, 565, 680, 393, 540 and 580, and the Eastman Chemicals Epolene "E" series of compounds.

Although they are used for various purposes, one of their most extensive uses is as an ingredient in wax emulsions. They are therefore often referred to as emulsifiable polyolefins.

There is no question regarding the efficacy of these carboxylated polyethylene or polyalkylene waxes or resins as rheological agents for paints or other dispersions of finely-divided solids in liquid media. For optimum usage, however, it would be best if they were available as finely-divided powders to be incorporated together with pigments or other finely-divided solids in the dispersion step.

However, carboxylated polyethylene powders of such fineness are not available, and they would be very difficult and expensive to manufacture by present technology. This is because the material is basically resilient and resistant to pulverisation. Thus, air milling or micronising, which would be methods of choice for producing powders, are not effective on such materials which tend to bounce when struck, rather than break or smash to produce powders. Hammer mills are slightly more successful, but are generally not as effective for obtaining the very fine powders required. In addition, the milling machinery becomes hot, and these polyethylenes tend to soften at elevated temperatures.

For this reason, cryogenic conditions are extremely helpful but they are also very expensive.

According to the present invention, a composition, e.g. in dispersion in a liquid, is a finely-divided solid comprising a substrate and a carboxylated polyalkene.

The invention is based on the discovery of certain methods whereby known polyethylene waxes may be supplied in powder form. These methods depend on combining polyethylene with adsorptive or absorptive substrates in such ways that the wax is adsorbed onto or absorbed into the substrate; such a mixture may then be ground.

The basic principle in all the methods described is the same. For example, polyethylene wax of the type described above is blended with a substrate, e.g. a pigment or resin or both, optionally using solvents or other liquids to aid in the blending, and the polyethylene is subjected to heat-processing so that it may be absorbed or adsorbed in situ by the substrate, as may be necessary to obtain a grindable powder. When pulverised or ground to a fine powder, the resulting product may be readily dispersed in solvent-based compositions wherein its rheological properties are beneficial. Both solvent-based paints and other fluid compositions benefit from the use of such rheological agents. For example, inks and dispersions of powders in liquids such as are used in herbicides, biocides, adhesives, sealants and caulks also benefit for final product use.The settling and caking of insoluble pigments or other powders dispersed in a liquid carrier are serious commercial problems, and such problems are greatly reduced by the use of the type of rheological agents herein described.

For practice of the invention, absorptive substrates such as clays of various crystalline configurations or states of sub-division such as bentonites, attapulgite clays, laminar clays, calcines clays and other such clays are used. Other suitable substrates are pigments, silicas with high absorption such as diatomaceous silicas, and calcined variants, and very fine silicas, e.g. manufactured from silicon tetrachloride and sodium silicate. Many types of substrates or combinations of substrates may be used that are absorptive and grind sufficiently well for micronisation.

One method of the invention comprises blending a substrate having absorptive properties with, say, commercially-available coarse powders of the polyethylene waxes. These commercially-available polyethylene powders are far too coarse to serve as a rheological agent. For the purpose of functioning as rheological agents, they should be finer than 200 U.S. mesh, and preferably finer than 400 U.S.

mesh. Generally speaking, finer powders are much preferred, since they provide greater effectiveness with minimum effect on other properties, such as gloss and surface uniformity, and they are also easier to incorporate in the compositions.

After mixing the coarse polyethylene granular powder with the pigment, the blend is heated with agitation until a temperature is reached at which the polyethylene wax melts. With continued mixing, the dispersed droplets of molten polyethylene wax are absorbed by the pigment. After complete absorption, the resulting powder, which agglomerates to some extent when subjected to this procedure, is cooled. The resulting powder is capable of being ground to the appropriate fineness.

It has been found that simple mixing of the absorptive substrate with the coarse polyethylene powder does not supply a suitable composition since it is not easily ground or milled to the fine particle size required for its intended use. Attempts to do so by air milling, for example, invariably result in a mixture of fine pigment and somewhat finer but still much too coarse polyethylene powder. For example, the methodology of US-A-3,252,820 does not work to produce a useful product.

Another method, somewhat similar to the one just described, comprises predispersal of the, say, polyethylene wax with approximately one-third its weight of a solvent into which the wax will dissolve at elevated temperatures. This moist mix is then stirred into an absorptive substrate, as described above, and the entire blend heated with agitation. The difference between this method and the one previously described is the temperature which must be reached in order to have the polyethylene absorbed by the substrate. Depending on the solvent used, this temperature is generally appreciably lower. This procedure has advantages in instances where the mixer is heated by hot water or low pressure steam, and the higher temperatures required to melt the polyethylene wax particles are unobtainable.The best solvents for this purpose are low boiling aromatics such as benzene, toluene, xylene, cumene and high flash aromatic naphthas such as mineral spirits, VM and P naphthas and mixed aliphatic fractions and aliphatics, although chlorinated solvents such as chlorobenzene and chlorinated butanes may also be used. The criterion for suitability is the ability of the polyethylene wax to dissolve in the solvent at elevated temperatures; highly polar solvents such as water and the lower alcohols are therefore unsuitable.

It is generally advantageous to select solvents which volatilise at temperatures close to that of boiling water, e.g. at 80 to 1 200C. The reason for this choice is that, during the heating and mixing steps, most of the solvent volatilises. For reasons of economy and pollution control, this volatilised solvent is preferably condensed and collected for reuse. The final product occasionally contains some small amount of residual solvent which is generally lost in the grinding step, especially when air mills are utilised.

Alternatively, solubilising solvents selected can be those compounds which have either very low volatility or substantially none. For example, all or part of the "solvent" may consist of wetting agents, resinous materials or plasticisers which may be liquid or solid at ambient temperature. These materials sufficiently disperse or dissolve the polyethylene wax at elevated temperatures so that it is absorbed or adsorbed by the substrate. Examples of such materials are non-ionic, cationic, anionic or amphoteric wetting or emulsifying agents of a wide range of HLB values.

Among the resinous materials that may be advantageously used are chlorinated paraffins, coumarone-indene, petroleum or terpene resins. One advantage of using hard, brittle and/or friable resins is that blends of these with the polyethylene wax thereby become more easily ground or milled to fine powders. By careful selection of the resin, and testing of various ratios of resin to polyethylene, it is possible to obtain fine powders, either using no pigments or fillers or using only relatively small amounts, which will serve as rheological agents. In some cases, the powders obtained from such a solid solution have advantages in ease of dispersibility, since the hard resin used readily dissolves in the solvents or liquid portions of compositions into which they may be incorporated.

Another method for blending the, say, polyethylene wax with the substrate to obtain a grindable or pulverisable powder with rheological properties comprises emulsification of the wax prior to blending.

Water will be driven off during the heating stage necessary for melting of the polyethylene wax and absorption/adsorption on the substrate. Some preliminary testing may be necessary to determine the best methods of incorporation. One satisfactory method comprises spraying the emulsion onto the pigment while the latter is mixed and heated in a fluid bed drier.

A further method is to blend the, say, polyethylene emulsion with the substrate and then precipitate the solids by use of an appropriate precipitant. The polyethylene is thus absorbed or adsorbed by the substrate during drying and may then be ground or pulverised to produce the very fine powders required.

One limitation in all these procedures is the absorptive capacity of the substrate for the polyethylene. Using an insufficient amount of substrate, or one of low absorptivity, as measured, for example, by the property known as oil absorption, results in powders which are difficult to grind, since they have too much "resiliency". Generally, concentrations of up to 40% w/w are reasonably easily obtained although this figure may be somewhat higher with some particularly absorptive substrates.

Substrates preferred for use in the invention are those of low colour and opacity, since these give the greatest flexibility for the formulation. However, coloured pigments may, of course, be used for special purposes. In addition, other materials may be used for reasons of compatibility or ease of incorporation. For example, hard, pulverised resins which are soluble in the liquid carrier of the dispersion in which it is to be incorporated may be used, either entirely or in part. If the composition to which it is to be added is to be burned off, and minimum ash is desired, a starch can be used. If the composition to which it is to be added is aqueous, a water-soluble substrate such as sugar or a watersoluble hard gum can be advantageously used.Suitable powders that may be used as adsorbers or absorbers of the polyethylene depend on the end use and include many materials which are well known in the art.

Extended polyethylene powders have been described, wherein the polyethylene resinous wax is generally a minor but sizeable component of the thixotropic composition. Further, substrates of high density or specific gravity which, although fine, are not extremely fine, may have some polyethylene absorbed therein in order to improve their non-settiing properties. Examples of such substrates are the denser calcium carbonates, red or yellow iron oxides, barium sulfate (barytes), chrome yellow, molybdate orange, titanium dioxide and red lead. Such substrates are used in major quantities in formulated compositions and are known to settle and pack hard. In general, they have low oilabsorption values and are not capable of absorbing or adsorbing very much polyethylene.However, because they are used commercially in high concentrations, a low percentage of polyethylene is adequate for the purpose of improving anti-settling characteristics.

While dispersions of polyethylene waxes of the type described in various solvents have been readily available for some time, they suffer from properties associated with pastes which are difficult to handle, use solvents which are not always those which are appropriate or desirable, and suffer evaporation of the solvents, causing caking and lack of uniformity, while the solvents used constitute an inflammability hazard and a pollution problem. Powders, however, have a wide application and do not present these disadvantages.

In addition, it has beenn found that the powders described and claimed herein show enhancement of activity over that to be expected from the polyethylene wax content alone. The presently-available polyethylene wax dispersions require heat in order to activate them. This requirement is frequently a problem, depending on the dispersion method and formulation used by the manufacturer. If sufficient heat is not developed in the dispersion step, the activity of the polyethylene wax as a rheological agent, to decrease substrate settling, for example, is so greatly impaired as to militate against its use. The powders, on the other hand, can be incorporated during the dispersion step, and show activity even under adverse temperature conditions, i.e. at temperatures below that required to activate the polyethylene wax in the solvent paste.At higher dispersion or incorporation temperatures, where both the powder and the paste forms develop their full potential as rheological agents, the powder will frequently show greater activity. The highly adsorptive/absorptive pigments and fillers used, often because of their absorptivity and particle shape, show evidence of activity as rheological agents.

However, this activity is of a low order unless they are modified, for example, as disclosed in, for example, US--AA-2,531,427 or 2,622,987.

The folowing Examples illustrate the invention.

It is to be understood that where the terms "adsorbed" and/or "absorbed" are used in this specification, they are used to mean incorporated into or combined with, either by chemical or physical forces, or by a combination thereof.

It is to be understood, that when "polyethylene" or "P/E" is used, it refers to the type described in the foregoing description, i.e. polyethylene or polyolefins with carboxyl groups attached thereto or contained therein.

EXAMPLES 1 and 2 50 g polyethylene powder (Eastman's E-1 0) and 50 g china clay are heated together to form a homogeneous melt. This mixture is allowed to cool on a Teflon-lined tray and then ground or pulverised.

The entire procedure is repeated using 50 g polyethylene powder (Eastman's E-1 4) and 50 g china clay.

EXAMPLE 3 50 g P/E (Eastman's E-1 0), 5 g tallow diamine, 45 g attapulgite clay and 40 g toluene are heated together to form a homogeneous melt. The mixture is transferred to a Teflon-lined tray and the toluene is allowed to evaporate. The mixture is then ground.

EXAMPLE 4 To a melt of 42 g P/E (Eastman Epolene E-1 0) were added 72 g toluene. During this mixing step there were added 54 g attapulgite clay and 6 g tallow diamine. Additional toluene was added as necessary. The product was spread on a tray to allow the toluene to evaporate and then ground to a fine powder.

EXAMPLE 5 40 g P/E (Eastman's Epolene E-1 0), 53 g attapulgite clay, 20 g china clay, 6 g tallow diamine and 120 g toluene were mixed and heated. The toluene was allowed to evaporate and the product ground.

EXAMPLE 6 40 g P/E (Eastman's Epolene E-1 0), 53 g attapulgite clay, 6 g tallow diamine, 20 g water and 75 g toluene were mixed and heated. The toluene and water were allowed to evaporate and the product ground.

COMPARATIVE EXAMPLE A slurry was prepared from 60 g attapulgite clay, 12 g china clay, 70 g methanol and 8 g tallow diamine. The product was spread on a tray to dry and then ground. It should be noted that there is no P/E in this composition.

EXAMPLE 7 40 g P/E (Eastman's Epolene E-1 0) were dissolved in 50 g toluene. 5 g water were then added and the mixture was heated during the addition of 45 g attapulgite clay. The resulting composition was poured into a tray to allow the solvents to evaporate. It was then ground.

TEST PROCEDURE Several of the finely ground powders prepared as described above were tested for their effect on stabilising dispersions of powders in a liquid medium. For this purpose, a coating system containing high density pigments known for their propensity for hard settling was used. A paste, System A, was prepared by mixing, using a high speed disperser, the following ingredients:: 1100 g titanium dioxide (R-900-DuPont) 1100 g barium sulfate (barytes) 500 g short oil alkyd, 41% soyabean oil, 42% phthalic anhydride, 50% solids in xylol (Beckosol 1307-50 RCI) The products of several of the previous Examples were incorporated through the use of a Quickie Mill, a laboratory mill consisting of four stainless steel cylinders each of which is filled with a composition and grinding medium, after which they are capped and placed in a holding mechanism which is shaken by a paint shaker, for simultaneous and identical dispersions. Each mill cylinder was charged with the following paste, System B: 125 g Paste "A" 25 g hi-flash aromatic naphtha 2 g extended P/E as described in above Examples (thixotrope).

The cylinders with their contents were heated in an oven for 45 minutes at 71 C (to obtain optimum activity). They were placed on the shaker mill referred to above for 15 minutes. To 130 g of paste B, made as described above, there were added 100 g of a "letdown" composition prepared from the following: 770 g short oil alkyl 83 g melamine-formaldehyde resin, 60% solids (Uformite MM-47-RCI) 135 g hi-flash aromatic solvent Visual observations were made and the samples were then allowed to stand overnight undisturbed. Settling evaluations as shown in Table 1 below were made the following day.

The 40% P/E/ paste/xylol thixotrope is a commercial material, used as a standard.

TABLE I

Thixotrope Viscosity Fineness of Grind Film Gloss Baked Settling (Krebs Units) (North standars 135 C/15 min. Gauge) None 53 7 85 Hard 40% P/E Paste/xylol 57 5 80 Soft-Med. Example 1 60 52 85 Very Slight Example 3 62 6-7 85 Very Slight Example 4 57 - - None Example 5 - - - Soft Example 6 63 7 80 oNone Comparative Example - - - Hard

The following Examples show methods of obtaining a grindable intimate blend of polyethylene and absorptive powders or pigments by mixing the absorptive powder or pigment with anionic and cationic emulsions of polyethylene.

EXAMPLE 8 An anionic polyethylene emulsion was prepared as follows: 1 80 g P/E (Epolene E-1 0 Eastman) were heated to 1 070C in order to prepare a melt. To this were added 82 g tall oil fatty acids and 3.8 g potassium hydroxide (85%) in 7.5 g ethylene glycol, followed by 32 g morpholine. This was mixed for 5 minutes after the addition, then added to 610 g water at 96CC with vigorous agitation. After emulsification was completed, the mixture was cooled with slow agitation. Yield = 860 g; % nonvolative (N.V.) = 27.1 P/E = 23% by calculation.

EXAMPLE 9 In order to prepare a higher concentration polyethylene emulsion, the procedure of Example 8 was repeated, using 1 50 g P/E (E-1 0), 30 g stearic acid (instead of tall oil fatty acid), 3.5 g potassium hydroxide (85%) (to dissolution), 7.5 g ethylene glycol, and 280 g water. Yield = 492 g; P/E = 34% (by calculation). The product was a clear, soft gel.

EXAMPLE 10 The product of this Example was prepared with a higher concentration of P/E and a lower emulsifier content. The procedure of Example 8 was repreated, but using 180 g E-1 0 (P/E), 1 5 g stearic acid, 2.3 g potassium hydroxide (85%), 5 g ethylene glycol, 21.3 g morpholine and 280 g water.

The product was a cloudy emulsion. It was passed through a screen to removes soine coagulum.

Yield = 427 g; % N.V. = 43.3%; P/E = 39% (calculated).

EXAMPLE 11 Example 10 was repeated using 360 g water, and adding more hot water to make up for water lost by evaporation. Yield = 517 g; P/E = 34%. The product was a cloudy, flowable gel.

EXAMPLE 12 Three sets of four samples of extended P/E powders were made with products from Examples 8 to 11.

A. To 54 g fine attapulgite clay were added 24 g tallow diamine/50% in methanol. To this there was added slowly, with continuous mixing (to give 40 g P/E in each Sample): Sample 1:174 g Example 8 Sample 2:118 g Example 9 Sample 3: 102.5 g Example 10 Sample 4:116 g Example 11 The product was dried and pulverised.

B. To 63 g fine attapulgite were added 24 g tallow diamine/50% in methanol. To this there was added slowly, with continuous mixing (to give 30 g P/E in each Sample): Sample 1: 130.5 g Example 8 Sample 2: 88.2 g Example 9 Sample 3:76.9 g Example 10 Sample 4: 86.9 g Example 11 The product was dried and pulverised.

C. To 72 g fine attapulgite were added 32 g tallow diamine/50% in MeOH. To this there was added slowly, with continuous mixing (to give 20 g P/E in each Sample): Sample 1:87.2 g Example 8 Sample 2:59 g Example 9 Sample 3: 51.3 9 Example 10 Sample 4: 58 g Example 11 The product was dried and pulverised.

The above twelve Sample powders were checked in a formulation similar to that used in the above Test Procedure. The results were similar. All viscosities were between 61 and 63 Krebs Units. The gloss values of the baked films were between 86 and 88. Settling tests indicated that series A Samples were slightly superior to series B Samples which were slightly superior to series C Samples. Since series A Samples had the highest concentration of P/E, and series C Samples had the lowest, this was as expected.

EXAMPLE 13 Polyethylene was dissolved in toluene by heating. Fine attapulgite was mixed into the melt. The mixture was spread out to dry and then ground. Quantities were as follows (in grams): Sample P/E (E-1 0) Toluene Fine Attapulgite Ratio Comment 1 80 272 240 25:75 Air dried and ground 2 96 224 224 30:70 Air dried and ground 3 112 207 208 35:65 Slower grinding 4 160 160 160 1:1 Difficult to grind It was found that increasing the amount of P/E increased the difficulty of obtaining a very fine powder.

Samples 1 and 2 of this Example were compared at several concentrations with a negative control (no thioxtrope) and a 40% solvent dispersion paste of polyethylene in an alkyd melamine semi-gloss baking enamel. In addition, Sample 2 was checked in four other formulations prepared as follows: A - Alkyd Melamine Semi-Gloss Baking Enamel Composition g/l titanium dioxide (R-900-DuPont) 220 barytes No. 1 (barium sulfate) 200 aromatic hi-flash naphtha 75 melamine formaldehyde resin solution/60% solids 52 alkyd resin (Beckosol 1 307-50) (Reichhold Chemical Inc.) 141 A paste was prepared as a dispersion from and above five ingredients.The following were then added: alkyd resin (Beckosol 1307-50) 397 thixotrope as tabulated The resulting Samples were ground in Quickie Mills for 30 minutes after pre-heating for 1 hour at 570C.

B - White Architectural Enamel Composition gfl titanium dioxide (R-900-DuPont) 250 barytes (barium sulfate) 100 long oil soyabean-pentaerythritol alkyd, 23% phthalic anhydride (Cargill BB-6-60%) 200 thixotrope as tabulated These four ingredients were dispersed in a high speed disperser.To this paste were added: long oil alkyd (as above) 380 mineral spirits 100 cobalt 6% drier 2.6 calcium 6% drier 7.6 anti-skinning agent 2 C - Iron Oxide Epoxy EsterAutomatic Primer Composition g/l barytes No. 1 (barium sulfate) 305 red iron oxide 40 Epotuf 38-402 (RCI) 76 xylol 36 VMP naphtha 43 A dispersion paste was prepared from the above five ingredients by dispersing on the high speed disperser for 10 minutes. Samples of the paste and thixotrope were processed in Quickie Mills with steel shot, pre-heated at 600C for 30 minutes, then dispersed for 30 minutes on a shaker.The following ingredients were then mixed into the Sample: (Epotuf 38-403-RCI) epoxy tall oil fatty acid ester/ 50% in xylol 232 (Beckamine 21-510) urea formaldehyde resin/60% in xylol-butanol 18 high-flash naphtha 22 xylol 26 VMP naphtha 183 calcium 4% drier 4 cobalt 6% drier 0.5 anti-skinning agent 0.5 D - Yellow Traffic Paint Composition gil medium chrome yellow 300 asbestine 3X 100 calcium carbonate (coarse ground-low oil absorption) 460 resin (Beckosol P319-60) (RCI) 310 A dispersed paste was prepared from the above ingredients. The Samples were placed in Quickie Mills with thixotrope and steel shot and dispersed as described under Example 1 3C above. The following ingredients were pre-dissolved and then mixed into the Sample: epichlorohydrin 1.3 chlorinated rubber (Parlon S-20 Hercules) 47 xylol 260 cobalt 6% drier 1.4 anti-skinning agent (methyl ethyl ketoxime) 2 II. The thixotropes and results are tabulated in Table II. Settling rates are from 0 (very hard) to 10 (no settling). Leneta sag ratings are from 0 (very poor sag resistance) to 12 (maximum sag resistance).

TABLE II Settling Rating Coating Additive Level (g/l) Viscosity (Krebs Units) Overnight 5 days Leneta System (24 Hr.) (6 Wks.) Sag Rating A None 0 70 - - 2 3-4 " P/E-40% in xylol 7 74 - - 7 3-4 " EX-13 (1) 7 70 - - 8 3-4 EX-13 (1) 10.5 71 - - 9 3-4 " EX-13 (1) 14 70 - - 9 3-4 " EX-13 (2) 7 77 - - 9 3-4 " EX-13 (1) 10.5 75 - - 9 3-4 " EX-13 (2) 14 76 - - 10 3-4 B None 0 87 90 ~ 1 4 " P/E 40% in mineral spirits 8 106 112 ~ 10 11 " EX-13 (2) 10.6 96 100 - 10 11 " EX-13 (2) + tallow diamine 11.4 100 105 - 10 11 C None 0 54 ~ 0 0 3 " P/E 40% in xylol 8 55 ~ 9 4 3 EX-13 (2) 10.5 55 - 7 4 3 " EX--13 (2) + tallow diamine 11.3 57 ~ 10 6 4 D Control 0 91 ~ 9 ~ 7 $ P/E 40% in xylol 6.0 91 - 10 - 12 " EX-13 (2) 6.0 91 - 10 - 12 " EX-13 (2) + tallow diamine 8.5 91 - 10 - 12 The following Examples demonstrate a technique wherein a polyethylene emulsion is precipitated onto an absorbent pigment to form a filterable slurry. The filter cake obtained may easily be dried and ground to a fine powder, constituting the thixotrope.

EXAMPLE 14 (1) To 100 g of polyethylene (E-1 0 - Eastman) were added 25 g tallow diamine, followed by 6.5 g acetic acid at 127 C. This mixture was slowly added to 370 g water at 93 C with rapid agitation and mixed while cooling. The gross weight was 450 g (some loss of water by evaporation); E-10 = 22%.

(2) To 27.3 g of the product (1) were added 14 9 fine attapulgite and 50 g water, with agitation. The solids were precipitated with 28% ammonia and filtered. Wet filter cake = 55 g. The dry product was easily broken up into a powder which was pulverised.

EXAMPLE 15 (1) An emulsion was prepared as described in Example 14, using 100 g polyethylene (E-1 0 - Eastman), 20 g tallow diamine, 5.2 g acetic acid and 370 g water. % P/E in emulsion product 21.7 % P/E.

(2) 196.6 g fine attapulgite and 790 g water were mixed together and then with 390 g of (1). To the resulting heavy slurry were added 600 g water, followed by 7 g NH28% to precipitate the solids, which were separated by filtration, dried and ground.

EXAMPLE 16 Example 15 was repeated using bentonite instead of attapulgite. Additional water was used as required for adequate agitation. the dried product was grey and hard, but capable of being ground into powder.

EXAMPLE 17 A P/E dispersion in water was prepared in a manner similar to Example 16, except that some fine attapulgite was added to the hot water prior to the addition of molten polyethylene (E-1 0) containing tallow diamine and acetic acid. The resulting dispersion contained 20% E-1 0 and 4% fine attapulgite.

The dispersion was very poor and gross separation into layers took place rather rapidly.

50 g of the product was, however, homogeneously blended with 20 g hydrous aluminium silicate (china clay - Burgess B-80, Oil Absorption = 41) dispersed in 50 g water. The PlE was precipitated with ammonia and additional water was added as required to maintain fluidity. The product was filtered, dried, and ground, % P/E = 30.

EXAMPLE 18 Using a somewhat larger amount of cchina clay, from another source (WCD No. 2459 Clay, Oil Absorption = 37), Example 17 was repeated. The polyethylene content in the ground, dried powder was 25%.

EXAMPLE 19 Example 17 was repeated, using 100 g dispersion product of Example 17,30 g china clay B-80 (Burgess) and 10 g betonite (No. 660) (Whittaker, Clark and Daniels). The product was light grey in colour.

EXAMPLE 20 To 275 g of the dispersion product of Example 17 were added 500 g water. While stirring this mixture, 110 g of china clay B-80 (Burgess) were sifted into it. While stirring the resulting thin mixture vigorously, there were slowly added 7 g ammonia/28%. The resulting slurry was filtered and the solid dried and pulverised.

EXAMPLE 21 To 160 g of polyethylene (Epolene E-1 0 - Eastman) were added 32 g tallow diamine and 9 g acetic acid at a temperature of 1 270C. With vigorous mixing, this mixture was added to 600 g water, at 930C, containing 30 g bentonite and 3 g acetic acid. The resulting emulsion was somewhat similar to that of Example 1 7. The primary difference was the use of bentonite instead of attapulgite. This emulsion contained 20.2% polyethylene and 3.8% bentonite.

EXAMPLE 22 65 g of china clay (B-80 - Burgess) were dispersed in 1 50 g water, and the dispersion blended with 150 g of the product of Example 21. The solids were precipitated with 4 g ammonia. The product was filtered, dried and ground.

EXAMPLES 23 to 26 The procedure of Example 22 was followed, using: (23) 47 g china clay (8-80 - Burgess), 1 00 g water, 87 g of the product of Example 15--(1)/21.7% P/E, and 2.5 g ammonia/28%; (24) 47 g attapulgite, 280 g water, 87 g Example 15--(1)/21.7% P/E, and 1.5 g ammonia/28%; (25) 47 g attapulgite (200 mesh and up), 220 g water, 87 g Example 15--(1)/21.7% P/E, and 2.5 g ammonia/28%; (26) 47 g china clay of high oil absorption (Glomax LL, Georgia Kaolin, oil absorptive = 60), 100 g water, 87 g Example 15--(1)/21.7% P/E, and 4 g ammonia/28%.

TEST PROCEDURE Formulation Composition Grams titanium dioxide (DuPont R-900) 37 barytes 34 thixotrope as indicated melamine-formaldehyde resin/60% solids (MM 47RCI) 8.7 aromatic hi-flash solvent 9 alkyd resin (Beckosol 1307) (50% solution) 24 The above ingredients were disposed on Quickie Mills with 200 9 steel shot after pre-heating for 1 hour at 570C. To 100 g of the above paste were added 57 9 Beckosol 1307/50% alkyd resin.

TABLE III Thixotrope Gms. Settling Viscosity Gloss Leneta 3 days (Krebs Units) Sag none 0 0 79 88 5 30% P/E gelled in xylol (standard) 1.2 6 82 88 5 Example 15 1.6 10 86 86 6 Example 16 1.6 6 79 87 5 Example 17 1.6 7 80 86 5 Example 18 1.6 7 79 88 5 Example 19 1.6 8 82 87 5 Example 20 1.6 8 79 87 5 Example 22 1.6 8 81 88 5 Example 23 1.6 9 80 88 5 Example 24 1.6 10 83 88 6 Example 25 1.6 10 82 81 6 Example 26 1.6 8 81 88 5 EXAMPLE 27 40 9 polyethylene (Epolene E-1 0- Eastman) and 60 9 70% chlorinated paraffin (Chlorowax 70--Diamond Shamrock) were mixed and melted together at 1 200C. The resulting melt was cooled, broken up and ground to a fine powder having thixotropic properties equivalent to that of 40% dispersion of polyethylene in solvent.

These experimental results illustrate the use of a hard resin as the extender.

COMPARATIVE EXAMPLE A solution was prepared by mixing 6 g tallow diamine into 14 g methanol. The solution was blended with 30 9 polyethylene (coarse powder) (AC-629-A-Allied Chem.). After warming and mixing to evaporate the methanol, 70 g of fine attapulgite were added, with mixing, to the residue.

Attempts to grind this mixture to a fine powder were unsuccessful.

EXAMPLE 28 A portion of the product of the preceding (Comparative) Example was placed in a beaker and heated to 1 250C with mixing. There was no clumping, although the mixture contracted in volume as absorption of the polyethylene took place. After grinding, a fine powder with thixotropic properties was obtained.

EXAMPLE 29 3 g of sulfonate castor oil were mixed with 1 5 g P/E coarse powder. To the moist mixture were added 35 g fine attapulgite. The mixture was agitated and heated to 1 300C. The mixture was held at this temperature for 5 minutes and mixing was continued, while cooling. The composition was ground to produce a fine powder with thixotropic properties. This Example illustrates the uses of an anionic dispersant with the extended polyethylene.

The Example below illustrates the use of several other powder extenders and the use of relatively small amounts of solvents to lower the temperature at which the coarse powdered polyethylene melts or dissolves and is absorbed on the powder extender.

EXAMPLE 30 A portion of P/E coarse powder was mixed with the solvents indicated below at about 300 C. To the moist slurry were added 21 g of the extender pigment indicated. This was placed in a boiling water bath and mixed well as the temperature of the mixture rose to 900C. At a temperature of about 750C, the properties of the mixture changed as the polyethylene melted, dissolved in the solvent, and became absorbed onto the extended powder. At a temperature of about 900 C, adsorption was completed and the solvent had evaporated. The compositions were then cooled and ground to fine powders with thixotropic or anti-settling properties.

TABLE IV Solvent Extenders Wetting Agent 4.5 g toluene attapulgite None 3 g toluene + 3 g methylene chloride fine attapulgite None 4.Sgtoluene+ 1.5g 1.8 g anionic methylene chloride fine attapulgite (added at the end) 4.5 g toluene calcium carbonate (Albacar W-5970) None 4.5 g toluene diatomaceous silica None 4.5 g toluene amorphous silica None

Claims (16)

1. A solid finely-divided composition with comprises a substrate and a carboxylated polyalkene.

2. A composition according to claim 1, in which the carboxylated polyalkene is a carboxylated polyethylene.

3. A composition according to claim 1 or claim 2, in which the substrate is a pigment.

4. A composition according to any preceding claim, in which the substrate is a clay.

5. A composition according to any preceding claim, in which the substrate is a silica.

6. A composition according to any of claims 1 to 3, in which the substrate is talc.

7. A composition according to any of claims 1 to 3, in which the substrate is calcium carbonate.

8. A composition according to any of claims 1 to 3, in which the substrate is a resin.

9. A composition according to any preceding claim, in dispersion in a liquid.

10. A composition according to claim 1, substantially as described in any of the Examples.

11. A method for producing a composition according to any preceding claim, which comprises incorporating a grindable substrate into the carboxylated polyalkene, and pulverising the thus-extended polyalkene-substrate product.

1 2 A method according to claim 11, in which the carboxylated polyalkene is adsorbed on the substrate.

13. A method according to claim 11, in which the carboxylated polyalkene is absorbed on the substrate.

14. A method for producing a composition according to any of claims 1 to 10, which comprises mixing and incorporating the carboxylated poiyalkene into a particulate substrate, coprecipitating the resulting mixture as a solid product, and drying and grinding the product.

1 5. A method for producing a composition according to any of claims 1 to 10, which comprises heating a mixture of powdered carboxylated polyalkene and a solid, particulate substrate, whereby the polyalkene melts and is absorbed by the substrate, and grinding the resulting product.

16. A method according to claim 1 5, in which the heating is carried out in the presence of a solvent, and the solvent is then removed.